John G. Gerber

Guidelines for the Evaluation and Management of Dyslipidemia in Human Immunodeficiency Virus (HIV)-Infected Adults Receiving Antiretroviral Therapy: Recommendations of the HIV Medicine Association of the Infectious Disease Society of America and the Adult AIDS Clinical Trials Group

Michael P. Dube, James H. Stein, Judith A. Aberg, Carl J. Fichtenbaum, John G. Gerber, Karen T. Tashima, W. Keith Henry, Judith S. Currier, Dennis Sprecher, and Marshall J. Glesby, for the Adult AIDS Clinical Trials Group Cardiovascular Subcommittee Indiana University, Indianapolis; University of Wisconsin, Madison; Washington University, St. Louis, Missouri; University of Cincinnati and Cleveland Clinic, Ohio; University of Colorado, Denver; Brown University, Providence, Rhode Island; University of Minnesota, St. Paul; University of California at Los Angeles; and Cornell University, New York, New York

Management of metabolic complications associated with antiretroviral therapy for HIV-1 infection: recommendations of an International AIDS Society-USA panel.

Objective: Alterations in glucose and lipid metabolism, lactic acidemia, bone disorders, and abnormal body fat distribution have been recognized recently as frequent complications associated with HIV‐1 infection and potent antiretroviral therapy, but limited data ate available regarding the appropriate management of these disorders. These recommendations were developed to guide physicians actively involved in HIV care in the management of metabolic complications that occur primarily within the context of potent antiretroviral therapy. Participants: A 12‐member panel representing international expertise in HIV‐1 patient care, antiretroviral therapy, and endocrine and metabolic disorders was selected in the spring of 2000 by the International AIDS Society‐USA, a not‐for‐profit physician education organization. Panel members met in closed meetings beginning in May 2000. All work was funded by the International AIDS Society‐USA; the panel members are not compensated for their participation. Evidence: The panel reviewed published results of clinical, epidemiologic, and basic science studies and data and abstracts presented at research conferences, primarily from 1997 to 2002. The panel also considered studies of the pathophysiology and treatment of similar metabolic abnormalities in noninfected persons. Emphasis was placed on results from prospective, randomized, controlled clinical trials when available. Process: For each metabolic complication, 1 or more member(s) reviewed and presented all available evidence to the panel, and then wrote a summary of the evidence and preliminary recommendations. Final recommendations were determined by full group consensus. The summaries were combined into a single working document and all panel members edited and approved all subsequent drafts. Conclusions: Carefully controlled studies to determine the incidence, etiology, risk factors, and most appropriate treatments for metabolic complications in HIV‐1 infection are urgently needed. In the absence of these data, and to prevent acute illness and mitigate long‐term risks, the panel recommends routine assessment and monitoring of glucose and lipid levels and assessment and monitoring of lactic acidemia and bone abnormalities if clinical signs or symptoms are detected. With the exception of body fat distribution abnormalities, specific treatments for these complications are also recommended. Successful long‐term antiretroviral therapy will require diligent monitoring and preemptive treatment of metabolic complications to optimize the riskbenefit ratio of antiretroviral therapies.

Pharmacokinetic interactions between protease inhibitors and statins in HIV seronegative volunteers: ACTG Study A5047.

Objective Lipid lowering therapy is used increasingly in persons with HIV infection in the absence of safety data or information on drug interactions with antiretroviral agents. The primary objectives of this study were to examine the effects of ritonavir (RTV) plus saquinavir soft-gel (SQVsgc) capsules on the pharmacokinetics of pravastatin, simvastatin, and atorvastatin, and the effect of pravastatin on the pharmacokinetics of nelfinavir (NFV) in order to determine clinically important drug–drug interactions. Design Randomized, open-label study in healthy, HIV seronegative adults at AIDS Clinical Trials Units across the USA. Methods Three groups of subjects (arms 1, 2, and 3) received pravastatin, simvastatin or atorvastatin (40 mg daily each) from days 1–4 and 15–18. In these groups, RTV 400 mg and SQVsgc 400 mg twice daily were given from days 4–18. A fourth group (arm 4) received NFV 1250 mg twice daily from days 1–14 with pravastatin 40 mg daily added from days 15–18. Statin and NFV levels were measured by liquid chromatography/tandem mass spectrometry. Results Fifty-six subjects completed both pharmacokinetic study days. In arms 1–3, the median estimated area under the curves (AUC)0−−24 for the statins were: pravastatin (arm 1, n = 13), 151 and 75 nguu.h/ml on days 4 and 18 (decline of 50% in presence of RTV/SQVsgc), respectively (P = 0.005); simvastatin (arm 2, n = 14), 17 and 548 nguu.h/ml on days 4 and 18 (increase of 3059% in the presence of RTV/SQVsgc), respectively (P < 0.001); and total active atorvastatin (arm 3, n = 14), 167 and 289 nguu.h/ml on days 4 and 18 (increase of 79% in the presence of RTV/SQVsgc), respectively (P < 0.001). In arm 4, the median estimated AUC0−−8 for NFV (24 319 versus 26 760 nguu.h/ml;P = 0.58) and its active M8 metabolite (15 565 versus 14 571 nguu.h/m;P = 0.63) were not statistically different from day 14 to day 18 (without or with pravastatin). Conclusions Simvastatin should be avoided and atorvastatin may be used with caution in persons taking RTV and SQVsgc. Dose adjustment of pravastatin may be necessary with concomitant use of RTV and SQVsgc. Pravastatin does not alter the NFV pharmacokinetics, and thus appears to be safe for concomitant use.

Mechanism of adriamycin cardiotoxicity: Evidence for oxidative stress

Abstract Adriamycin is a widely used anticancer agent but the cumulative dose-dependent cardiotoxicity severely limits the use of Adriamycin in the treatment of neoplastic diseases. Recent evidence suggests that Adriamycin forms reactive free radical species which may oxidize cellular components and produce the cardiomyopathy. Sulfhydryl donors and antioxidants have been effective in preventing acute Adriamycin cardiotoxicity in animal models presumably by scavenging the free radicals generated by Adriamycin. The sulfhydryl donors, namely cysteamine and N-acetyl cysteine, do not interfere with Adriamycins antitumor activity. The results from these studies give considerable hope that the chronic cardiotoxicity from Adriamycin may be attenuated in people, thereby givinh additional therapeutic benefit from this antitumor agent.

Interactions between antiretroviral drugs and drugs used for the therapy of the metabolic complications encountered during HIV infection.

Treatment of HIV infection with potent combination antiretroviral therapy has resulted in major improvement in overall survival, immune function and the incidence of opportunistic infections. However, HIV infection and treatment has been associated with the development of metabolic complications, including hyperlipidaemia, diabetes mellitus, hypertension, lipodystrophy and osteopenia. Safe pharmacological treatment of these complications requires an understanding of the drug-drug interactions between antiretroviral drugs and the drugs used in the treatment of metabolic complications. Since formal studies of most of these interactions have not been performed, predictions must be based on our understanding of the metabolism of these agents.All HIV protease inhibitors are metabolised by and inhibit cytochrome P450 (CYP) 3A4. Ritonavir is the most potent inhibitor of CYP3A4. Ritonavir and nelfinavir also induce a host of CYP isoforms as well as some conjugating enzymes. The non-nucleoside reverse transcriptase inhibitor delavirdine potently inhibits CYP3A4, whereas nevirapine and efavirenz are inducers of CYP3A4.Drug interaction studies have been performed with HIV protease inhibitors and HMG-CoA reductase inhibitors. Coadministration of ritonavir plus saquinavir to HIV-seronegative volunteers resulted in increased exposure to simvastatin acid by 3059%. Atorvastatin exposure increased by 347%, but exposure to active atorvastatin increased by only 79%. Conversely, pravastatin exposure decreased by 50%. Similar results have been obtained with combinations of simvastatin and atorvastatin with other HIV protease inhibitors. Thus, the lactone prodrugs simvastatin and lovastatin should not be used with HIV protease inhibitors. Atorvastatin may be used with caution.Although there are no formal studies available, calcium channel antagonists and repaglinide may have significant interactions and toxicity when used with HIV protease inhibitors because of their metabolism by CYP3A4. Sulfonylurea drugs utilise mainly CYP2C9 for metabolism, and this isoenzyme may be induced by ritonavir and nelfinavir with a resulting decrease in efficacy of the sulfonyl-urea. Losartan may have increased effect when coadministered with ritonavir and nelfinavir because of the induction of CYP2C9 and the expected increase in formation of the active metabolite, E-3174.Overall, well-designed drug-drug interaction studies at steady state are needed to determine whether antiretroviral drugs may be safely coadministered with many of the drugs used in the treatment of the metabolic complications of HIV infection.

Protein Binding in Antiretroviral Therapies

There is marked variability in the extent to which the three classes of antiretroviral (ARV) drugs bind to plasma proteins (<5 to >99%). Protease inhibitors (PIs), with the exception of indinavir, are more than 90% protein bound, mainly to alpha1-acid glycoprotein (AAG). Efavirenz, a nonnucleoside reverse transcriptase inhibitor (NNRTI), is more than 99% bound, mainly to albumin. Nucleoside reverse transcriptase inhibitors (NRTIs) are not highly protein bound. The pharmacological activity of ARV drugs is dependent on unbound drug entering cells that harbor the human immunodeficiency virus (HIV). There has been concern that changes in protein binding could impact on antiviral activity and management. However, for PIs and NNRTIs, and for many drugs given orally, altered plasma binding would not be expected to influence the average exposure to unbound (active) drug after chronic oral dosing. Nevertheless, there will be a change in the relationship between total and unbound concentrations that will be important if, as part of therapeutic drug monitoring, the total rather than the unbound drug is measured. Measuring drug concentrations that are needed to inhibit different HIV strains (wild type and drug resistant) in vitro could also cause confusion because most methods employ bovine serum in the assay medium, and unbound concentrations are not directly measured. Estimating unbound drug concentrations in human plasma and in incubation media can be highly method dependent and thus may affect the calculated IC50 (the concentration of drug that results in 50% inhibition of viral replication). Because inhibitory quotients (IQs = C(trough)/IC50) are becoming part of pharmacokinetic/pharmacodynamic (PK/PD) analyses of clinical trial data, the strengths and weaknesses of the methods used for the determination of unbound drug concentration in plasma and in vitro systems--ultracentrifugation, ultrafiltration, and equilibrium dialysis--need to be understood. Consensus on standard procedures must be reached. In June 2002, a panel of experts assembled by the Forum for Collaborative HIV Research met in Washington, DC, to review the basic principles of protein binding of ARV drugs, and to discuss the impact that changes in plasma protein binding may have on the PKs and activity of ARV drugs as well as on therapeutic drug monitoring. The purpose of the meeting was to discuss the following topics: (1) basic principles of protein binding and how changes in binding can impact on drug PKs and drug exposure in vivo, (2) variability in plasma protein binding among patients taking ARV drugs, (3) the impact of HIV infection and concomitant diseases on the extent of plasma protein binding, (4) the likelihood of clinically relevant drug interactions at the level of plasma protein binding, (5) the evidence that measuring unbound concentrations of ARV drugs in the plasma of patients gives more meaningful information than total drug concentration and, therefore, should be considered in routine therapeutic drug monitoring of ARV agents, (6) optimal method(s) for measuring the unbound concentration of drugs in vitro (for IC50 determination) and in vivo, and (7) future studies that need to be considered to fully understand the importance of plasma protein binding in therapeutic drug monitoring. This report summarizes the topics discussed at this meeting. It guides the reader through the discussions that allowed the panel to formulate a series of statements regarding the significance of plasma protein binding of ARV drugs when studied in vitro and in vivo. The roundtable participants also identified research priorities that are important for understanding the sources of inter- and intraindividual variability in protein binding in patients. These include obtaining data on unbound as well as on total concentrations in PK studies; looking at variants of AAG and whether they differ in binding affinity; and emphasizing the importance of developing a standard procedure for drug susceptibility assays used to determine IC50 values.

Effect of efavirenz on the pharmacokinetics of simvastatin, atorvastatin, and pravastatin: results of AIDS Clinical Trials Group 5108 Study.

Efavirenz (EFV) is associated with hyperlipidemia when used in combination with other antiretroviral drugs. EFV is a mixed inducer/inhibitor of cytochrome P450 (CYP) 3A4 isozyme and may interact with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors that are primarily metabolized via CYP3A4. To assess the drug-drug interaction of EFV used in combination with simvastatin (SIM), atorvastatin (ATR), or pravastatin (PRA), an open-label trial was conducted in 52 healthy adult HIV-seronegative subjects across AIDS Clinical Trials Group sites in the United States. Subjects received 40 mg of SIM, 10 mg of ATR, or 40 mg of PRA daily on days 0 through 3 and days 15 through 18. EFV was administered daily at a dose of 600 mg on days 4 through 18. SIM, ATR, and PRA concentrations were determined before and after EFV, and EFV concentrations were determined before and after statins. EFV reduced SIM acid exposure (area under the curve at 0 to 24 hours [AUC0-24h]) by 58% (Wilcoxon signed rank test, P = 0.003) and active HMG-CoA reductase inhibitory activity by 60% (P < 0.001). EFV reduced ATR exposure by 43% (P < 0.001) and the total active ATR exposure by 34% (P = 0.005). EFV administration resulted in a 40% decrease in PRA exposure (P = 0.005). SIM, ATR, and PRA had no effect on non-steady-state EFV concentrations. In conclusion, EFV, when administered with SIM, ATR, or PRA, can result in significant induction of statin metabolism. The reduced inhibition of HMG-CoA reductase activity during coadministration of EFV may result in diminished antilipid efficacy at usual doses of SIM, ATR, and PRA.

Drug/Drug Interaction Between Lopinavir/Ritonavir and Rosuvastatin in Healthy Volunteers

Objectives:This open-label, single-arm, pharmacokinetic (PK) study in HIV-seronegative volunteers evaluated the bioequivalence of rosuvastatin and lopinavir/ritonavir when administered alone and in combination. Tolerability and lipid changes were also assessed. Methods:Subjects took 20 mg of rosuvastatin alone for 7 days, then lopinavir/ritonavir alone for 10 days, and then the combination for 7 days. Intensive PK sampling was performed on days 7, 17, and 24. Results:Twenty subjects enrolled, and PK data were available for 15 subjects. Geometric mean (±SD) rosuvastatin area under the concentration time curve (AUC)[0,τ] and maximum concentration (Cmax) were 47.6 ng·h/mL (±15.3) and 4.34 ng/mL (±1.8), respectively, when given alone versus 98.8 ng·h/mL (±65.5) and 20.2 ng/mL (±16.9) when combined with lopinavir/ritonavir (P < 0.0001). The geometric mean ratio was 2.1 (90% confidence interval [CI]: 1.7 to 2.6) for rosuvastatin AUC[0,τ] and 4.7 (90% CI: 3.4 to 6.4) for rosuvastatin Cmax with lopinavir/ritonavir versus rosuvastatin alone (P < 0.0001). There was 1 asymptomatic creatine phosphokinase elevation 17 times the upper limit of normal (ULN) and 1 liver function test elevation between 1.1 and 2.5 times the ULN with the combination. Conclusions:Rosuvastatin low-density lipoprotein reduction was attenuated with lopinavir/ritonavir. Rosuvastatin AUC and Cmax were unexpectedly increased 2.1- and 4.7-fold in combination with lopinavir/ritonavir. Rosuvastatin and lopinavir/ritonavir should be used with caution until the safety, efficacy, and appropriate dosing of this combination have been demonstrated in larger populations.

The prostaglandin system. A role in canine baroreceptor control of renin release.

We used the nonfiltering kidney model with contralateral nephrectomy to investigate the site where prostaglandins influence renin release. Adrenergic influences on renin release were excluded by renal denervation, bilateral adrenalectomy, and a continuous propranolol infusion. In this model, reduction of renal perfusion pressure by 50% increased renal venous renin activity from 3.10 ± 0.66 to 13.14 ± 3.8 ng of angiotensin I/ml per hour within 10 minutes (P < 0.05). This increase in renin activity was abolished by pretreatment with indomethacin, 8 mg/kg, but not by the sodium carbonate buffer in which indomethacin was dissolved. Infusion of arachidonic acid into the artery of the nonfiltering kidney at a rate of 10 + −g/kg per minute for 20 minutes also increased the renal venous renin activity from a baseline of 2.35 ± 0.37 to 5.45 ± 2.45 ng of angiotensin I/ml per hour by the end of the infusion. This effect of arachidonic acid was blocked by indomethacin. A fatty acid, 11,14,17-eicosatrienoic acid, which is not a substrate for cyclooxygenase, had no effect on renin release in this model. These data indicate that the prostaglandin system can affect the renal baroreceptor mechanism for renin release. Stimulation of prostaglandin synthesis by providing arachidonic acid increased renin secretion, and inhibition of cyclooxygenase abolished the ability of the renal baroreceptor to respond to a reduced perfusion pressure with renin release. Furthermore, this interaction is probably due to products of the renal cortical cyclooxygenase since transport of prostaglandins from the medulla to the cortex in tubular fluid cannot occur in the nonfiltering kidney.

Factors modifying the early nondiuretic vascular effects of furosemide in man. The possible role of renal prostaglandins.

Animal experiments have suggested that salt-balance, prostaglandin synthesis, and renal function are important determinants of the nondiuretic vascular effects of furosemide. To investigate the influence of these factors in humans, we studied 10 normal volunteers and five anephric patients. The volunteers were studied on three occasions: when on a 10 mEq/day sodium diet, on a 250 mEq/day sodium diet, and on a 10 mEq/day sodium diet with indomethacin, 200 mg/day. The anephric patients were studied immediately after dialysis. Plethysmographic methods were used to measure venous capacitance and blood flow in the calf before, and at 5, 10, and 15 minutes after furosemide, 80 mg, iv. Blood was obtained before and 15 minutes after furosemide for determination of plasma renin activity by radioimmunoassay and of plasma 6-keto-prostaglandin F1 alpha by chromatography-mass spectrometry. We found that furosemide significantly increased venous capacitance in the calf of the normal volunteers on a low salt diet. Indomethacin, high salt intake, or lack of renal function was sufficient to inhibit this effect. Plasma renin activity increased only in the group that had the increase in venous capacitance. Limb blood flow decreased gradually in the 15 minutes following administration of furosemide in the normal volunteers, regardless of salt balance or indomethacin, but remained unchanged in the anephric patients. Plasma 6-keto-prostaglandin F1 alpha was less than 30 pg/ml in all samples. Indomethacin concentration averaged 1.3 micrograms/ml in volunteers on the drug. To determine whether indomethacin, salt intake or renal function affected another venodilator, we studied an additional group of normal and uremic volunteers who received 0.6 mg nitroglycerin sublingually.(ABSTRACT TRUNCATED AT 250 WORDS)